The Molecular Biology Core is a critical component of the NIDA P30 Center at Temple University. The Molecular Core offers services to investigators that involve either short- or long- term use of molecular techniques. This Core provides three types of services. First, the Core supports the design and construction of molecular constructs for the expression of genes of interest. This will include, for example, the expression either in vitro or in vivo of opioid or cannabinoid receptors. These molecular constructs will permit a variety of studies of interest to collaborating investigators including the analysis of receptor-mediated signaling processes and the analysis of the cellular trafficking of receptors (or other genes of interest). Second, the Molecular Biology Core will provide gene expression analysis both in vitro and in vivo. The Core provides highly quantitative analysis of mRNA and miRNA expression using RT-PCR, northern blot analysis, RNase protection analysis, and new to this renewal application, the novel FISH flow (PrimeFlow) analysis. The Core also offers comprehensive transcription factor function analyses. Third, the Core provides genotyping services for the Animal Core and to other investigators breeding mutant animals. Services are provided for investigators who span a variety of disciplines and work is carried out in direct collaboration with the investigator. The Molecular Biology Core is particularly interested in continuing efforts to promote the use of molecular techniques to study the role of drugs of abuse in the host-parasite interaction with HIV. The Core has been highly successful in engaging NIH-funded investigators from many disciplines in collaborative research projects that have advanced the understanding of the actions of drugs of abuse and their interplay with the immune system and with HIV. By combining the expertise of investigators with diverse interests, new perspectives and potentially novel investigations can be developed.